Cranial nerve · one in each half of the brain
Vagus nerve (X)
Also called Cranial nerve X, CN X, Tenth nerve, Nervus vagus
The "wandering" nerve that runs from your brainstem to your heart, lungs, and gut.
The vagus is the longest cranial nerve. It leaves the brainstem and wanders down through the neck into the chest and belly, reaching the heart, lungs, and most of the gut. It is the main line of the body's calming "rest and digest" system: it slows the heart, helps digestion, and controls the muscles of the throat and voice box. Most of its fibers actually carry news the other way, from your organs up to your brain.
Where it is
It leaves the side of the medulla, exits the skull near the ear, and runs down the neck beside the big neck artery and vein. It then branches out to the heart, lungs, stomach, and intestines.
What it does
Brake on the heart
It constantly slows your heartbeat. Without it, your resting heart would beat noticeably faster.
Runs digestion
It helps make stomach acid, squeezes food along the gut, and tells the brain when you are full.
Voice and swallowing
It controls the voice box and most throat muscles, so you can speak, sing, and swallow.
Body news feed
Most of its fibers carry signals from the organs to the brain, reporting on things like stretch, nutrients, and inflammation.
Breathing reflexes
It carries signals from the airways and lungs, including those that can trigger coughing.
Think of it as a two-way hotline between your brain and your inner organs: the brain sends calm-down orders, and the organs send constant status reports back.
Works with
- Medulla oblongataIts main control centers sit in the medulla, right next to the centers for breathing and blood pressure.
- HypothalamusThe hypothalamus steers the body's autopilot, and the vagus is one of its main ways to reach the organs.
- InsulaOrgan signals it carries eventually reach the insula, which helps create your sense of what is happening inside your body, like a full stomach or a racing heart.
- Glossopharyngeal nerve (IX)In the gag reflex, nerve IX feels the touch and the vagus makes the throat squeeze.
- Accessory nerve (XI)The two leave the skull side by side through the same opening.
- AcetylcholineIt slows the heart by releasing acetylcholine, the first nerve chemical messenger ever discovered.
When it goes wrong
How doctors check it
You say "ahh" while the doctor watches the soft palate rise evenly. If one side is weak, the little dangling uvula is pulled toward the healthy side. A hoarse voice or trouble swallowing are other clues.
Fainting
A strong vagus surge, triggered by things like fear, sudden pain, or standing for too long, can suddenly slow the heart and drop blood pressure, causing a faint.
Vagus nerve stimulation
A small implanted device that sends gentle pulses along the vagus is an approved treatment for some people with epilepsy that medicines do not control, and for some hard-to-treat depression.
For learning only, not medical advice. If you have a health concern, talk to a doctor.
Surprising facts
- The first chemical messenger used by nerves was found using the vagus. In 1921 Otto Loewi showed that fluid from a frog heart slowed by its vagus could slow a second heart. The discovery later won him a share of the 1936 Nobel Prize.
- A tiny branch of the vagus even carries feeling from part of your ear canal and eardrum.
- Deep breathing is one way to switch on the body's calming "rest and digest" system, partly by stimulating the vagus.
By the numbers
Where the name comes from
From the Latin vagus, "wandering", the same root as "vagabond" and "vague". It earned the name because it roams so far through the body.
Learn it in a lesson
- The brainstem and cranial nervesLife support and the nerves of the head. A short guided lesson in 3D.
Quick quiz
3 questions. Your answers are saved and come back in your daily review.
Which of these is a job of the vagus nerve (X)?
Show the answer
Brake on the heart. It constantly slows your heartbeat. Without it, your resting heart would beat noticeably faster.
Brake on the heart. It constantly slows your heartbeat. Without it, your resting heart would beat noticeably faster.
The vagus nerve (X) is part of which larger structure?
Show the answer
Cranial nerves. It belongs to the cranial nerves.
Cranial nerves. It belongs to the cranial nerves.
Which part fits this description? "Like a two-way hotline between your brain and your inner organs: the brain sends calm-down orders, and the organs send constant status reports back."
Show the answer
Vagus nerve (X). It is the vagus nerve (X). The "wandering" nerve that runs from your brainstem to your heart, lungs, and gut.
Vagus nerve (X). It is the vagus nerve (X). The "wandering" nerve that runs from your brainstem to your heart, lungs, and gut.
These parts now come back in your daily review, just before you would forget them.
Practice it and its neighbors in 3DSources
- Neuroanatomy, Cranial Nerve 10 (Vagus Nerve), StatPearls, NCBI Bookshelf
- 17.3 How Does the Brain Talk to the Immune System?, OpenStax, Introduction to Behavioral Neuroscience
- Otto Loewi: Facts, NobelPrize.org
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Explore the vagus nerve (X) in 3D
Turn it around, zoom inside and see how it connects to the rest of the brain, then test yourself with quick quizzes.
Open it in 3D